Luminous electric heater



April l 1924. v l,488',755

V F. KuHN ET Al.

Patented Apr. 1, 1924.

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To all whom it may concem:

Be it known that we, Fmx Kumt and Jer A. HAND, both citizens of the United States of America., residin at Detroit, i' n 6 the county of Wayne and tate of Michigen, have invented certain new and useful mprovements in Luminous Electric Heat-` ers, of which the following is a specification, reference being had therein to the accompan ing drawings.

This invention relates to luminous electric heaters and particularl relates to eleco er a mimmum obstruction to the waves o'r Irays reflected from the concave surface; which will approximate as closely as poible the efiect of heat radiating from the focal point of the reflector and which will throw the heat rays or waves uniformly upon the reflecting surface at all sides of the unit. f

In the accompanying drawing: ao Figure 1 is a front view of e heater;

Figure 2 is a view of the 'same in side elevation and partial section. g

In these views the reference character 1 designates a concave reflector, preferabl el- Ul lipsoidal, and 2 a resistor-coil upon a ho low insulatory re 8, said core' and coil being co-axial with the reflector and being substantially symmetrical with res ct to the focus thereof. The diameter o said core 4 and of the coil wound thereupon increases gradually from the extremities of the unit to its center as is clearly seen in Figure 2. The rear end of said core is engaged within a tubular holder 4 g assing through the reflector and embrac by an annular flange 5 rearwardly pro'ecting from the reflecton.

said holder an the heatin unit carried thereby being axially adjustl le in said enibracing flange to 'properly adjust the unit with respect to the focus. The rear portion of the holder 4 is filled with insulatory' material 6 in which a pair of terminale 7 are imbedded, said terminale projecting rear;

wardly beyond the holder. The refleetor is formed at its periphery with a return-bent flange 8, which flange is embraced by a ring '9 flanged inwardl at its rear edge, as indicated at 10, the ange 10 engagmg behind the flange 8 to restrain said ring against forward removal from the reflector. Said ring -is formed with a series of spaced hooks 11` which peripherally engage a wire guard 12 of concave shape, said guard preferably havirng thelshape of a rosette, as is shown by ince the convolutions of the coiled resistor 2 are co-axial with the reflector, the heat radiated from said resistor will impinge upon the reflecting surface substantial y uniformly at all sides of the heatin unit. The co-axial relation of said unit wit the reflector is further advantageous, in that yit minimizes the obstruction offered thereby to the reflected radiation of heat. The tapering of the unit from its center to its ends is advantageous, in that the convolutions at the inner end portion of the unit do not obstruct radiation from the convolutions adjacent the center of the unit and similarly the convolutions ad'acent the outer end of 'the unit offer no o sruction to radiation from the convolutions of greater diameter.

By the use of an ellipsoidal reflector, the

reflected rays are' given a substantially conical form, the apex of the core of rays being the focus conjugate. to that at which the heating unit is mounted. By varying' the diflereiitial relation between` the major and minor axes of the ellipse transcribing the ellipsoidal surface, the distance of the apex of the cone of rays from the reflector may Vbe varied without change in thel maximum diameter of the reflector. While theoretically the rays from a concave surface must emanate from the focus thereof in order to be reflected uniformly in a predetermined direction, it has been found that an ellipsoidal refiector will collect heat rays originating anywhere close adjacent to its focus and converge them as indicated iii dotted lines in Fi' re 2.

t has been found that with the same resistor a much 'greater heat radiation is secured when the same is coiled as above described instead of being given the ordinary cylindrical Shape.

What we claim as our invention, is

1. In a luminous electric heater, the combination with a concave reflector, of 4a guard therefor arched across the front of said refiector, an annular member ripherally mounted u n the reflector, an a series of hooks carried by said annular member to which said guard is detachably en aged.

2. In a luminous electric heater, t e combination with a concave reflector, of a rin encircling the reflector at the front thereo and a guard arched over the front of the refiector detachably engaged with said ring at a plurality of points.

3. In a luminous electric heater, the combination with a concave reflector formed with a return-bent annular flange at its periphery, of a ring embracing the return-bent flange of the reflector and restrained thereby against forward displacement, and a guard arched over the front of the reflector and peripherally attached to said ring.

4. In a luminous heater, the combination with an ellipsoidal reflector, of a heatin unit located substantially at the focus o said reflector and coaxial therewith, said unit having a diameter gradually increasing from its extremities to an intermediate point thereof.

5. In a luminous heater, the combination with a concave reflector, of an electrical heating unit comprising a core of gradually va ing diameter and a resistor wound on core, said iinit being mounted with its axis substantially coinciding with the central axis of the reflector.

6. In a luminous heater, the combination with a concave reflector, of an electrical beating unit comprising a core member having its diameter gradually decreased from its center to its extremities and a resistor wound upon said. core member, said unit being mounted with its lon 'tudinal axis substantially coiiicidin wit the central axis of the refiector, w ereby the heat raya will be reflected in substantial parallelism..

' said unit being moun :mms

7. In a luminous heater, the combination with a concave reflecter, of an electrical heating unit comprising a coil resistor having its convolutions successively varied in diameter and a mounti with the axis of said resistor substantiall coinciding with the central axis of the re ector. 8.' In an electric heating unit adapted for use in conjunction with a concave reflector, an msulating core member ha its diameter graduall decreased from its Vcenter to its ends, an a resistor wound upon said core member, said unit being, adapted for mounting with its longitudinal axis co-incident withthe central axis of the reflector, whereby the heat rays will be reflected in substantial parallelism.

9. In an electric beating unit adapted for use in con'unction with a'concave reflector, a resistor forming a coil and having the diameter of its convolutions gradually decreased from the center to the extremities of said coil, and a mountin for said resistor with its longitudinal axis coincident with the central axis of the reflector, whereby the radiation. from' said resistor convolutioiis will be unifoi'mly distributed over the surface of said refiectorz and the reflected rays arran in substantial parallelsin.

10. n an electric heatmg unit ada ted for use in conjunction with a concave re ectorz a spirally grooved insulating core having its diameter gradually decreasing from its center for said resistor i portion to its extremities, and a resistor wound u n said core in said ve and formed o coiled wire, said unit being adapted for mounting with its axis coincident with the center axis of the reflector, for the purposedescribed.

In testimony whereof we afix our signatures.

FRANK KUHN. JAY A. HAND. 

